I've been in the same position but with a younger child. First, the missing person registry isn't going to help. Only way to find him is to get the local police to keep an eye out. I also took pictures to the neighboring town's police. I went out looking for cops on the street and handed out his picture. They don't actively look for runaways. And they don't pick them up just for being a runaway unless you've reported him which you obviously have.
Until Oct 28 I can give you some advice. After 18 I haven't had to face yet.
You have to tell the cops what you want done with him. You won't know that until they actually pick him up and then circumstance will partially decide for you. But right now, the cops aren't going to talk to you about it unless you have a relationship with them. Cops don't talk hypotheticals. Options:
1. Get him into a mental health placement. He was in group home before. Go back to the agency that helped with that placement and ask for another when he's found. In most cases it then becomes their job to find a bed, not yours. In fact, what has been the case with me is that if you have signed temporary custody to a group home, agency, CPS for purposes of placement that is still in effect while he's missing. So technically when he's found the cops should call them to pick him up, not you.
2. A shelter if available bed or even available shelter.
3. Jail. If he has anything on him (stolen property, drugs) let them arrest him. He'll be there until a hearing anyway. At hearing you can ask judge to order him into some kind of placement or keep him in jail. Depending on the charge, how he pleads, etc the judge might do it. If he's already on probation you can call his PO and ask the PO to get judge to agree to hold him. Have to tell you though, this never got me anywhere... PO isn't interested or judge won't agree when it's only a mental health or sub abuse problem. Presumably if they determined that he's a danger to society they might. But being a danger only to himself they don't get very interested.
4. Hospital. If you can prove a mental health problem, and prior diagnosis is key (based on your profile you don't have one), you can apply for a judge to sign a committment order. So when he's found he's committed for a 72 hour hold.
5. Asking cops to take him to ER for an evaluation is always a possibility. If he's violent when they pick him up they should take him to ER anyway for an evaluation. But often the ER won't admit him. If he needs detox they should admit him. Hospital SW will then get involved in finding a bed for him if they don't admit him.
6. Sub abuse program. If you have one arranged before he's picked up (which is going to be difficult) you can have him taken there. If not, let him stay in one of the other short term options and then get him admitted to rehab. Reason it's difficult for this option is that no place will admit him without interviewing him. I have never talked to a for-profit place that you are going to personally pay for.. maybe they'd admit him without interview? In addition to interview, the rehabs won't talk to you unless you have funding. They don't keep beds open for kids who might be found. No matter what you did beforehand there might not be a bed when he's ready to go.
After 18 I believe the options change as follows:
1. Option gone, you can't force placement.
2. Any shelter is voluntary on his part. If he wants to go they might call around for a bed, at best. But it would be up to him to agree to shelter and possibly to find one.
3. Same. But as an adult judge isn't going to listen to you. You can express your opinion to his lawyer but that's all.
4. Same.
5. Same
6. voluntary on his part. Funding, unless you're paying, is virtually impossible. At best, huge wait for inpatient placement with public or charity funding. There are some rehabs you don't have to pay for, mostly all religion based.
You do need to understand that after 18 the cops won't be calling you if/when they pick him up. He's an adult. If he asks cops to call you they probably will. If they arrest him he gets one call and would have to choose to call you. Hospital, ER or otherwise won't discharge him to you unless he wants that. So at 18 your options are extremely limited unless he voluntarily accepts something. If he's got a criminal charge big enough for a judge to order something he might agree to it rather than prison. I have to disagree that the cops will pick him up or arrest him just because you, cops, everyone knows he's using and selling. They will only pick him up and/or arrest him if they see him doing something or catch him with something on him. Actually, in an effort to help me, local cops would frisk mine every time they saw him on the street. Never caught him with more than cigs, a lighter or a pocket knife. But obviously law to protect citizens/ prevent cops from abusing the system says that they can't pick someone up, hold them or arrest them without evidence. At least as it relates to picking up someone re a criminal issue. And what "everyone knows" is heresay, not evidence.